| Adaptive look up table : a graphical simulation component for recursively updating numeric data storage in table form -> Monitor Keywords |
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  Adaptive look up table : a graphical simulation component for recursively updating numeric data storage in table formRelated Patent Categories: Data Processing: Structural Design, Modeling, Simulation, And Emulation, Modeling By Mathematical ExpressionThe Patent Description & Claims data below is from USPTO Patent Application 20070225951. Brief Patent Description - Full Patent Description - Patent Application Claims
BACKGROUND [0001] The invention relates generally to graphical block diagram modeling. [0002] Dynamic systems may be modeled, simulated and analyzed on a computer system using graphical block diagram modeling. Graphical block diagram modeling graphically depicts mathematical relationships among a system's inputs, states and outputs, typically for display on a graphical user interface. [0003] In a graphical block diagram model, graphical blocks describing the static or dynamic behavior of corresponding physical components are graphically connected to each other in order to simulate the aggregate behavior of the combined physical system or plant. The behavior of a physical system, which may include mechanical or electronic components, can be described in terms of numeric data stored in table (matrix) or multi-dimensional array format in computer memory. The resulting table or array is referred to as a lookup table and is well known in the art. [0004] In the simpler two-dimensional case, lookup tables correspond to matrices studied in the field of mathematics. Each element of a matrix is a numerical quantity, which can be precisely located in terms of two indexing variables. At higher dimensions, lookup tables are represented as a collection of matrices, whose elements are described in terms of a corresponding number of indexing variables. In the area of computer programming and simulation, lookup tables provide a means to capture the behavior of a physical system. More specifically, the behavior of a system with M inputs and N outputs can be approximately described by using N M-dimensional lookup tables. [0005] Lookup tables can be generated by experimentally collecting or artificially creating the input and output data of a system. In general, as many indexing parameters are required as the number of input variables. Each indexing parameter may range within a pre-determined number of values, which are called breakpoints. The set of all breakpoints corresponding to an indexing variable is called a grid. Hence, a system with M inputs has M grids or sets of breakpoints. For given input data, the breakpoints (in breakpoint sets corresponding to the input variables) are used to locate the array elements where the output data of the system are stored. For a system with N output data values, N array elements are located and the corresponding data are stored at these locations in a computer memory. [0006] In prior lookup table schemes, once a lookup table is created using the system input and output data, the corresponding multi-dimensional array of values can be used in applications without the need for regenerating the system output data. Only the input data is required to locate the appropriate array elements in the lookup table, and the approximate system output data can be read from these locations. Therefore, a lookup table captures an input-output mapping of a static or dynamic system in the form of numeric data stored at pre-determined array locations. [0007] Prior graphical block-based modeling and simulation tools, e.g., Simulink.RTM. from The MathWorks Inc, support graphical lookup table blocks that provide for such a static mapping of input-output behavior of a physical system. Because the behavior of actual physical systems can vary with time due to wear, environmental conditions, and manufacturing tolerances, however, the "static" lookup table block may not provide a valid representation of the plant characteristics at a given time. SUMMARY [0008] The present invention is therefore directed towards a graphical lookup table block that takes into account the time-varying nature of the system behavior that it is used to describe. In particular, the present invention provides methods and systems for adapting the values of a lookup table over time to account for additional data from the physical plant or system that it models. [0009] In one aspect, the invention provides methods and apparatus, including computer program products, for table lookup. The methods include providing to a graphical block diagram model a graphical block that defines a lookup table and having inputs for receiving input data, and using the graphical block to update content stored in the lookup table based on received input data. [0010] Particular implementations of the invention may provide one or more of the following advantages. [0011] Unlike prior static lookup table blocks, the adaptive lookup table block of the present invention always provides a valid representation of plant dynamics even though plant behavior may be time varying. Moreover, the underlying adaptation techniques of the adaptive lookup table block are robust against reasonable measurement noise and provide appropriate filtering of noisy output measurements. [0012] The graphical block can be used in a simulation program to dynamically and efficiently update the data stored in a lookup table. That is, the block forms part of a larger simulation model of a physical system, which is represented in a graphical simulation environment. This approach is highly reusable and presents a flexible interface to a user. [0013] The adaptive lookup table defined by the graphical block can be realized in other forms, such as computer programs or code embedded in microprocessor hardware for real-time applications. Supplied in a suitable simulation environment as a graphical simulation block, the method or methods defining the underlying lookup table of the block can be used to automatically generate computer code for embedded applications. [0014] Other features and advantages of the invention will be apparent from the following detailed description and from the claims. DESCRIPTION OF DRAWINGS [0015] FIG. 1 is a block diagram of an exemplary system simulation environment in which processes of a graphical block diagram modeling/simulation module for graphical block diagram model development and execution, as well as code generation, are executed. [0016] FIG. 2 is an exemplary screen display from a GUI of a computer system executing the model editor of the graphical block diagram modeling/simulation module (of FIG. 1) during development of a graphical block diagram model that includes an adaptive lookup table block. [0017] FIG. 3 is an exemplary block parameter dialog box in which a user specifies block parameters for the adaptive lookup table block. [0018] FIG. 4 is a block diagram of an adaptive table lookup corresponding to the adaptive lookup table block shown in FIG. 2. [0019] FIG. 5 is a depiction of an exemplary, two-dimensional cell-based (0.sup.th order) adaptive table lookup. [0020] FIG. 6 is a depiction of an exemplary, two-dimensional point-based (1.sup.st order) adaptive table lookup. [0021] FIGS. 7A and 7B are exemplary plant surface plots generated using measured data and using data produced by adaptive (cell-based) table lookup, respectively. Continue reading... Full patent description for Adaptive look up table : a graphical simulation component for recursively updating numeric data storage in table form Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this Adaptive look up table : a graphical simulation component for recursively updating numeric data storage in table form patent application. ###  How KEYWORD MONITOR works... a FREE service from FreshPatents1. Sign up (takes 30 seconds). 2. Fill in the keywords to be monitored. 3. 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